Problem: Sum of Unit Fractions (click here to see the problem statement)

My Solution. We are looking for

where , , and

 

Simplifying,

We have,

 

 

If we let ,

then

So,

 

Which implies that :

 

Which can only be true when , so

Using the relationship , I set up a table

 

 

 

So the answer to the question,

"Which of these fractions (, where n is a positive integer) may be expressed as the sum of two different unit fractions of integers?" appears to be: ALL OF THEM.